1. Field of the Invention
The present invention relates to phone security systems, and more particularly pertains to a new and improved phone screen security system for blocking unwanted incoming phone calls and unauthorized outgoing phone calls. The present invention is designed to give an individual the security of an unlisted phone number, without incurring the inconvenience and expense of changing their present phone number. The screening system of the present invention requires a caller to input a security code number before the ringer on the individual's phone is actuated. The system includes a programmable code detect circuit which allows the access code to be easily and repeatedly changed.
2. Description of the Prior Art
Various types of phone security systems are known in the prior art. A typical example of such a phone screen security system is to be found in U.S. Pat. No. 4,520,233, which issued to J. Smith on May 8, 1985. This patent discloses a telephone security system which intercepts and screens incoming calls and directs them to a terminal through a modem. The security system prevents completion of a connection to a terminal equipment unless the incoming call provides a predefined access code and the call is found to have been made from a remote subscriber station to which the predefined access code has been assigned. U.S. Pat. No. 4,621,334, which issued to J. Garcia on Nov. 4, 1986, discloses a personal identification system for verifying whether a particular individual is a member of a group of authorized individuals. The system measures time delays between successive strokes of a keyboard as the individual enters his name. A timing vector is constructed from the time delays and is statistically compared with a stored timing vector derived from the authorized individual. If the timing vectors are statistically similar, the individual will be permitted access. U.S. Pat. No. 4,634,811, which issued to W. Curtin et al on Jan. 6, 1987, discloses a call screening system which enables incoming calls for various telephone extensions to be directed to another telephone extension in the system for screening the calls. U.S. Pat. No. 4,674,115, which issued to D. Kaleita et al on June 16, 1987, discloses a programmable telephone switcher which routes an incoming call to a selected telephone, dependent on preestablished access codes dialled by the caller. The device provides call hold, call forwarding an automatic dialling. The device generates ringer signals for directly energizing the ringer circuits on standard telephones. U.S. Pat. No. 4,680,785, to T. Akiyoma et al which issued on July 14, 1987, discloses a personal signalling communication system wherein a personal identification number is assigned to each telephone user, and an arbitrary person is called via wireless by dialling a corresponding personal calling number.